Ford’s revelation that the new F-150 will use aluminum, not steel, for its body panels was enough news to overshadow nearly everything else about America’s next favorite vehicle. But in the wake of its debut, we’re beginning to hear the more-standard questions—the ones that start with “Why” and end with “Get real.” You know the kind. Why is there no version with a stick? Why isn’t there a targa version? Why can’t I buy an F-150 with a 30-mm rotary cannon in the bed? But then you get to the “Why isn’t there a diesel version?” and the question can’t be dismissed with a reference to reality.

Citing unnamed sources, The Truth About Cars claims that “Ford is apparently at work on a 3.0-liter V-6 diesel,” adding that it’s code-named “Lion” and would arrive in roughly 2018—about the time of the new F-150’s midlife overhaul.

We’ll parse this in just a moment, but first, here’s what Ford’s VP of global product development, Raj Nair, has said on the subject recently. It’s not promising:

“We obviously have diesels in the lineup, and diesels are great if you are going to be consistently towing heavy payloads. And we feel Super Duty trucks are a better solution for that customer,” he told Automotive News last month.

“We don’t see the dynamics for an F-150 diesel right now. If you go through the math, your payback is much longer and consumers are smart enough to know that,” Nair said to Edmundsin July.

Meanwhile, “Lion” is the internal nickname for the diesel V-6, developed a decade ago jointly by Ford and PSA Peugeot-Citroën. It’s all-but extinct. Jaguar and Land Rover still use a 3.0-liter version, as Europeans overwhelmingly buy their big European luxury cars with 3.0-liter six-cylinder engines. That and a 2.7-liter version were once used widely in Ford, Peugeot, and Citroën models, but have now been phased out in favor of diesel fours. (Ford does, by the way, still offer the 2.7 in the extraordinarily low-volume Australian-market Territory SUV). This is the engine that Ford will use as the basis for an F-150 diesel? Or even the internal code name?

The reason that Ford and Peugeot-Citroën dropped the “Lion” diesel V-6 is that mainstream customers in Europe, the world’s largest and only significant market for diesel cars and SUVs, have moved on to diesel fours. What this means is that if Ford wants to develop a new six-cylinder diesel engine, it can’t look to Europeans for any meaningful number of sales. And without enough volume, there’s no profit on a brand-new engine.

So, to return to our original question: Why isn’t there a diesel engine in the new F-150? And why are we skeptical that one is coming soon? We’ve got a disinterested-sounding head of product planning on the one hand, and an obsolete code name and shrunken global demand on the other. This evidence, like it or not, is pretty real.